New Study on Butterflies Links Warming Climate to Human Activities

butterfly cocoon photo

Photo via internets_dairy via Flickr CC

It's no surprise to hear that butterflies are emerging earlier than usual - we've been witnessing that for several years now. But Researchers from the University of Melbourne have looked at the ever earlier emergence of butterflies is due to a climate being warmed by greenhouse gasses, and they state that not only are the results the first concrete evidence of a link between greenhouse gases and the timing of a natural event, but that it also shows that human activity is the cause of the warming. The researchers are hoping to show that by understanding how human activity is impacting one species like the butterfly, we can better predict how a warming temperature will affect other species. The Telegraph reports, "The team found that on average, the Common Brown butterfly (Heteronympha merope) has emerged earlier and earlier over the last half century, with an average of 1.6 days per decade over a 65 year span. Researchers from the University of Melbourne said that the findings tally with a corresponding increase in temperature of 0.14 degrees Celsius per decade over the same period. "

The researchers have found a strong correlation between this change in butterfly behavior and greenhouse gasses for which humans are responsible.

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Professor David Karoly said, "Scientists have previously observed that biological events are happening progressively earlier in spring over the past few decades. This new work has tied the earlier emergence of butterflies directly to a regional temperature increase, and has tied the temperature increase very strongly to increases in greenhouse gas concentrations caused by humans."

Lead author of the study Dr Michael Kearney, from the Department of Zoology, stated, "Studies such as ours will allow better forecasting of these shifts [in seasonal life cycle events] and help us understand more about their consequences."

Indeed, the change in season cycles is a major issue with animals who depend upon certain food sources to appear in the right abundance in the right areas in order to survive. For example, arctic sea birds which depend on precise timing for seasons in order to feed, breed and migrate. A shift in when seasons starts has wide-reaching effects for flora and fauna across the board, and butterflies - which often need particular plants and themselves act as a food source for other animals - can have far reaching impacts if they're emerging several days earlier than they were just decades ago.

By taking a look at the changes in butterflies over the last 65 years and layering that with greenhouse gas increases over the same period can be a tricky business - and obviously one that many are quick to debate - but the correlation is clearly strong. Yet, regardless of where one falls on the debate about why the planet is warming, the fact that species' cycles are shifting in such a clear way is alarming.

More on Seasonal Cycles Shifting with Warming
Global Warming Causing Plant, Bird and Insect Species to Appear Earlier than Expected
Your First Season of Allergies? Global Warming Could Be to Blame
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